Conventionally, in a caster including a solenoid operated brake mechanism of Japanese Patent Laid-Open No. 2001-58503, constitution is disclosed in which, for example, a caster frame, a pair of caster wheel supported on both ends of a horizontal shaft of the caster frame rotatably by the horizontal shaft, and a plunger moving forward/backward with respect to the caster frame by exciting the solenoid are provided, a hook interlocking with the plunger is provided on the caster frame, and an engagement portion engaging/disengaged with the hook is provided on a side surface of the caster frame of the caster wheel, and by turning on/off a switch provided on an arm rest of standing auxiliary chair, for example, the solenoid is excited, whereby the plunger is vertically moved.
Moreover, in a self-help device for indoor movement in Japanese Patent Laid-Open No. 2012-210237, a brake mechanism in which a caster is braked by a load in a predetermined range detected by a load sensor is provided, and regarding the brake mechanism, constitution having a motor capable of forward/backward rotation disposed on a mounting portion of the caster, a warm gear driven by the motor, a pressing-down arm driven by the warm gear, a rotating-shaft stop gear and a caster-wheel stop arm driven by the pressing-down arm, and a spring as an interference preventing mechanism for enabling operations of both the caster rotating-shaft stop gear and the caster-wheel stop arm is disclosed.
Since they can both omit a pedal or a lever used in a brake operation of a conventional caster, even in the case where a target such as a bed, a chair, a table or the like to which the caster is attached is installed in a narrow place, the brake operation can be performed by a switch or a load sensor at hand and thus, the brake operation can be performed easily.
However, in the former, the solenoid is operated by turning-on/off of the switch, while in the latter, a load applied on a seat surface of a seating portion is detected so as to perform the brake operation, and thus, there are problems that the brake control is not performed due to malfunction of the brake mechanism and the like or if the brake is not fully engaged, it cannot be confirmed.
Particularly, in National Publication of International Patent Application No. 2004-516991, in a roller or particularly a caster type roller capable of fixing a rotating operation of a driving wheel and a turning operation of the running wheel, including an operation shaft penetrating a control cam of the roller, and has an electric motor act on the operation shaft through a gear mechanism so as to drive the operation shaft, constitution in which the electric motor acts on the operation shaft using an electric motor shaft through the toothed gear mechanism is disclosed.
In the caster type roller, since the electric motor and a coil portion of the motor are connected to each other in a series, they extend in one way which makes obstruction, and the caster type roller including the electric motor cannot have its stem mounted on a normal cylindrical mounting portion and needs to be mounted to a carrier of a chassis through an attachment, and thus, the caster type roller including the electric motor cannot be used singularly, and there is also nonconformity that the electric motor protrudes long to the outer side.